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    <script>
        //演示1
        var f1 = function(a) {
            return a;
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        console.log(f1(3))

        var f11 = a => a
        console.log(f11(8))

        //演示2
        var f2 = function(a,b) {
            return a+b;
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        console.log(f2(3,4))

        var f22 = (a,b) => a+b
        console.log(f22(5,5))
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